This invention relates generally to dishwashers and more specifically to a selective washing arrangement for an automatic domestic dishwasher.
The present invention is applicable to a dishwashing machine of the the type disclosed in U.S. Pat. No. 3,077,200 having an upper and lower wash rack wherein a horizontally rotatable spray arm is disposed beneath the lower rack which is rotatable under the reactive force of liquid discharged from that arm. A tubular housing affixed to the rotatable spray arm adjacent the pivotal axis thereof and extending upwardly therefrom also receives liquid and has telescopically mounted thereon an extensible spray tube which moves to an extended position under pressure of liquid. This spray tube in turn has one or more orifices arranged to direct a rotating spray of liquid against the upper rack. This arrangement insures liquid under pressure is continuously directed to both the upper and lower rack.
This prior art arrangement requires that enough water be provided to keep both the spray arm and spray tube primed, with a resulting flow rate on the order of between 30-40 GPM being typical. Further, it should be noted that since dishwashers use hot water in carrying out the washing operation, the energy usage in supplying enough hot water to insure effective operation of both the spray arm and spray tube is also a factor. Typically, since a dishwasher proceeds through several cycles of cleaning and rinsing, and since the dishwasher is drained and refilled during each cycle of operation, the amount of water used, and particularly hot water, is also a factor from an energy standpoint.
It is, accordingly, an object of the present invention to provide a washing system wherein the amount of water used is substantially reduced while maintaining the effective washing ability of the dishwasher.
Another object of the present invention is to provide means for alternating the flow of water between the spray arm and the spray tube.
Another object of the present invention is to reduce the overall GPM flow of water through the pump system while increasing the pressure of water directed at the dishware from either the spray arm or spray tube.